This brief seeks to :
a) Give a brief overview of the club scoring system
b) Stress and remind players of the need for care and accuracy in the traveller recording.
c) Give the results access options for members.
d) Clarify some of the reasons for occasional wide variations in individual results.
I'm sure most members will have remarked at some time, how can a pair score an overall 'top' one week and on occasions, given the same partner and club conditions, a 'bottom' the next?, prompting remarks like “I don't understand this game,” at least when it comes to the scoring !.
Having recently been added to the club's scorers (we now have three), I feel it appropriate to give a brief outline of the process as to how the scores are arrived at. The club now uses in common with most other clubs, 'ScoreBridge' a computer assisted program that calculates and compares the results for each hand against the top score attained for that hand by all players, then displaying it as an individual percentage achieved together with the relevant master points earned.
It is important to stress that this is obviously dependant upon the collection and input of all the scores from the traveller sheets for all players during any one session assuming always that both east west and north south have agreed to those scores at the time of playing and that contract details and pair numbers are correctly noted. Any errors made at this stage would not necessarily be picked up by the computer program.
All too often, from other scorers comment and already from my own experience, player names and or pair numbers are either missed or incorrectly noted to the traveller sheets leading to inputting difficulties for the scorer having to judge whether scores and or pair numbers are correct or appropriate. Assuming these difficulties can be overcome by a tedious process of elimination, the scoring results can finally be input, an output display produced and transmitted to the EBU for computation and update of each members master points record.
When it comes to the weekly results outcome, long established members will have observed and likely concluded that a large slice of chance and luck comes into the equation effecting overall results, not necessarily limited to such factors as :
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Regular partner or not and your understanding with partner of your bidding systems.
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Where seated, whether N/S or E/W and how strong the oppositions playing ability.
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The playing difficulty or otherwise of the hands as dealt.
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Yours and oppositions playing ability.
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Whether you achieve a 'top' by skilful play, or are given one by the oppositions play!
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Whether lady luck is with you or not for some of those finesses.
On the choice of table movement, this is largely dictated by the number of players / tables, how many hands can be realistically played in the time available and whether a single winner or two winner result is preferable. There are numerous choices available for this, usually either a Mitchell or Howell movement. Each in their own way being a compromise between ease of use, members preference and whether considered to be the fairest way of assessing members performances against each other.
Some members might consider their best measure of performance to be judged against all other members as in a one winner movement. Others might feel it fairer to be compared to other N/S or E/W players sitting in the same position and playing the same hands. The boards and opposition however, will not necessarily be the same for each player pairing and therefore still a compromise.
The choice of movement also affects the degree of fairness by virtue of the *balance of the movement to give as far as possible equal chance for N/S & E/W players percentage scores. To help achieve this balance and in some cases, to avoid duplication of playing the same hands, the use of relays and arrow switching is often used or in the case of Howell movements, a player movement card which attempts to equal up the balance as much as possible for fairness to all players. This is not however an exact science, with the published EBU suggested movements being quoted as 'balanced as far as possible'. As always this is a compromise between practicalities, ease of use and players / club's preference.
On the subject of accessing your session results, members have three options, if you have access to a computer, the results are shown on this website under 'results' or from the EBU website click on member log in option, key in your EBU membership number which will then retrieve all your sessions played with their results. Finally, if you have no computer access, you can wait to the following weeks play where a printed output will be on display.
On member grading assessment, the EBU's current approach, is to average out players weekly percentage results over several months, so ironing out some of the highs and lows of each members performance before calculating their overall Master Points ranking.
So at the end of the day, if every playing session were always perfectly balanced in fairness, it might be a bit boring if the same players were always top. Given those elements of chance and luck, at least gives everyone the chance sometimes to have a good result!.
Perhaps it is just as important to enjoy the company of other fellow players and the exercising of the 'grey matter', rather than getting too concerned about weekly session results, after all, you usually know whether you have played well or otherwise! There is still no reason not to strive over time to improve your playing ability which will eventually show in your EBU grading, good luck and enjoyable play to all.
George Basnett.
Another view on the subject :
Balanced movements in bridge
Posted 07-01-09 by ianmac
The controversial issue of balance in bridge movements has been around for nearly as long as duplicate bridge. Since the 1930s people have been searching for the best balanced movements with claims for the best coming from Mr. Charles Kennedy in the 1930s, Dr. Lawrence Rosler in the 60s, Mr.J. R. Manning in the 70s and more recently professor OlofHanner.
The mathematics of balance and the measure of competition have been known since John Manning published a paper on the subject in 1979 and more recently a measure of bias has been defined precisely by Dr. Ross Moore in 1992. Even so and despite knowing the existence of this applied mathematics, Hans-Olof Hallen, and Per Jannersten (HHJ) published their most excellent book “Movements a fair approach” in 1994 claiming their movements were the best available.
Closer examination now shows that their incomplete movements disagree with the mathematics and their reasons are very questionable.
So what is balance?Balance refers to the fairness of the movement: all pairs have the same advantages during the event. A completely unbiased movement is the fairest of all. For any given situation and requirements, the movement with the least bias is the most desirable and should be used in preference to any other.
Another term used for this is balanced comparisons. Manning also calls this the measure of competition between all pairs.
Let us consider what is involved in comparison or comparing scores between pairs on a board.The match-point scoring method underlies the understanding of comparison and by definition is the comparison of results of all pairs who play a board.
Other than how well you play a hand,there are three other potential influences on the result, all outside your control: The quality of the pairs sitting in the same direction as yourself (say group 1) The quality of the pairs sitting opposite to those in group 1 (say group 2). The quality of the pair sitting opposite to you (your head-to-head opponent).
Call these factors 1 to 3. Each member of group 1 can play well and take one match-point from your score. Call these pairs your foes. Each member of group 2 can play well against group 1 opponents and add one match-point to your score. Call these pairs your allies. Your head-to-head opponent can play well and take as many match-points from your score as there are other tables in the movement (by scoring a "top"). Call this pair your opponent. A good pair will play well more often and a weak pair less often. Ideally each pair should have a fair share of these influences for the movement to be balanced.
Balance is not an issue where all pairs have the same opposition and the same comparisons. The completed Mitchell movement is the best example. There are two winners and two fields,the stationary pairs playing against the moving pairs and being compared with the other stationary pairs and vice versa. Only factor1 has any influence as 2 and 3 are equal for all pairs.
The complete one winner event is more complicated but balance is achievable. The Howell movement is the typical example. Carefully selected Howell movements can be very well balanced, particularly with an even numbers of tables. In these balanced cases factors 1, 2and 3 are the same for each pair giving a movement that is as equitable as possible.
Note in these Mitchell and Howell movements all rounds are played and the movements are defined as complete. The real problem for balance arises with incomplete movements. This is where there is one winner but all pairs do not meet. Typical examples are the ¾ Howell and the switched Mitchell.
In these cases there are two groups of pairs, those moving and those stationary. The stationary pairs do not meet each other and the moving pairs meet a mixture of the stationary and moving pairs.
This is where“Movements a fair approach” disagrees with the applied mathematics.
*References and further reading :
www.ebu.co.uk
www.marvinfrench.com/pl/bridgetopics/fairness.pdf
www.ebu.co.uk/publications/Laws and Ethics Publications/Bridge Movements – the Maths.pdf
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